CATALYTIC METHOD FOR THE REDUCTIVE AMINATION OF POLY(OXYTETRAMETHYLENE) DIACETATES

METHODE CATALYSEE D'AMINATION PAR REDUCTION DE DIACETATES DE POLY(OXYTETRAMETHYLENE)

English Abstract

CATALYTIC METHOD FOR THE REDUCTIVE
AMINATION OF POLY(OXYTETRAMETHYLENE) DIACETATES
(Docket No. 81,023-F)
ABSTRACT OF THE DISCLOSURE
Poly(oxytetramethylene) diamines useful in the prepara-
tion of polyamide and polyurea elastomers are prepared by the
catalytic reductive amination of a poly(oxytetramethylene)
diacetate feedstock under reductive amination conditions in
the presence of ammonia and hydrogen using a hydrogenation/
dehydrogenation catalyst composed of, on an oxide-free basis,
about 70 to 75 wt.% of nickel, about 20 to about 25 wt.% of
copper, about 0.5 to 5 wt.% of chromium and about 1 to 5 wt.%
of molybdenum.

Claims

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The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A method for the catalytic reductive amination of a
poly(oxytetramethylene) diacetate in the presence of hydrogen
and ammmonia in order to provide the corresponding poly(oxy-
tetramethylene) diamine, which comprises the step of:
conducting said reductive amination reaction of said
poly(oxytetramethylene) diacetate in the presence of a
catalyst composed of nickel, copper, chromium and molybdenum
and containing, on an oxide-free basis, about 70 to 75 wt.% of
nickel, about 20 to about 25 wt.% of copper, about 0.5 to 5
wt.% of chromium and about 1 to 5 wt.% of molybdenum,
said poly(oxytetramethylene) diacetate having the
formula:
<IMG>
(I)
wherein n represents 0 or a positive number having
a value of 1 to about 50.
2. A method as in claim 1 wherein the catalyst is
composed of about 70 to 78 wt.% of nickel, about 20 to about
25 wt.% of copper, about 0.5 to 3 wt.% of chromium and about
1 to 3 wt.% of molybdenum.

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3. A method for the catalytic reductive amination of a
poly(oxytetramethylene) diacetate in order to provide the
corresponding poly(oxytetramethylene) diamine, which comprises
contacting said poly(oxytetramethylene) diacetate with excess
ammonia and hydrogen in the presence of a catalyst composed of
nickel, copper, chromium and molybdenum under reductive
amination conditions including a temperature within the range
of about 150° to about 220°C. and a pressure of about 100 to
about 10,000 psig,
said catalyst containing, on an oxide-free basis,
about 70 to 75 wt.% of nickel, about 20 to about 25 wt.% of
copper, about 0.5 to 5 wt.% of chromium and about 1 to 5 wt.%
of molybdenum,
said poly(oxytetramethylene) diacetate having the
formula:
<IMG>
(I)
wherein n represents 0 or a positive number having
a value of 1 to about 50.

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4. A method as in claim 3 wherein the catalyst is a
pelleted catalyst composed of about 70 to 78 wt.% of nickel,
about 20 to about 25 wt.% of copper, about 0.5 to 3 wt.% of
chromium and about 1 to 3 wt.% of molybdenum and wherein the
reaction is conducted continuously by passing the poly(oxy-
tetramethylene) diacetate, ammonia and hydrogen through a bed
of said pelleted catalyst under said conditions of temperature
and pressure at a space velocity of about 0.1 to about 20
grams per hour of said poly(oxytetramethylene) diacetate, per
cc of said catalyst.
5. A method for the continuous catalytic reductive
amination of a poly(oxytetramethylene) diacetate in order to
provide the corresponding poly(oxytetramethylene) diamine,
said method comprising the steps of:
continuously passing said poly(oxytetramethylene)
diacetate, ammonia and hydrogen through a bed of a pelleted
hydrogenation/dehydrogenation catalyst under reductive
amination conditions including a temperature within the range
of about 150° to about 220°C. and a pressure of about 100 to
about 10,000 psig, at a space velocity of about 0.1 to about
20 grams per hour of said poly(oxytetramethylene) diacetate
per cc of said catalyst, and

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substantially quantitatively recovering a poly(oxy-
tetramethylene) diamine corresponding to the poly(oxytetra-
methylene) diacetate from the products of the reductive amina-
tion reaction,
said catalyst consisting essentially of, on an
oxide-free basis, about 70 to 75 wt.% of nickel, about 20 to
about 25 wt.% of copper, about 0.5 to 5 wt.% of chromium and
about 1 to 5 wt.% of molybdenum,
said poly(oxytetramethylene) diacetate having the
formula:
<IMG>
(I)
said poly(oxytetramethylene) diamine having the
formula:
H2N-CH2-CH2-CH2-CH2-[-O-CH2-CH2-CH2-CH2-]n-O-CH2-CH2-CH2-CH2-NH2
(II)
wherein n represents 0 or a positive number having
a value of 1 to about 50.

Description

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CATALYTIC METHOD FOR THE REDUCTIVE
AMINATION OF POLY(OXYTETRAMETHYLENE) DIACETATES
(Docket No. 81,023-F)
BACKGROUND OF THE INVENTION
Technical Field of the Invention
This invention relates to a method for the catalytic
reductive amination of a poly(oxytetramPthylene) diacetate in
order to provide the corresponding poly(oxytetramethylene)
diamine in high yield and with good selectivity.
More particularly, this invention relates to a method for
the catalytic reductive amination of a poly(oxytetramethylene)
diacetate in the presence of hydrogen and ammonia under reduc-
tive amination conditions wherein the reaction is conducted in
the presence of a catalyst composed of nickel, copper,
chromium and molybdenum and containing, on an oxide-free
basis, about 70 to about 75 wt.% of nickel, about 20 to about
25 wt.% of copper, about 0.5 to 5 wt.% of chromium and about
1 to 5 wt.% of molybdenum.
Still more particularly, this invention relates to a
process wherein a poly(oxytetramethylene) diacetate is reacted
with excess ammonia and hydrogen in the presence of a nickel,
copper, chromium, molybdenum catalyst in order to provide a
reaction product comprising the poly(oxytetramethylene)
diamine corresponding to the poly(oxytetramethylene) glycol
feedstock.

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Prior Art
Methods for the preparation and use of poly(oxytetra-
methyl) glycols are disclosed in Smith et al. U. S. Patents
No. 3,824,198, No. 3,824,219, and No. 3,824,220, patented
July 16, 1974. Other patents disclosing methods for making
and using poly(oxytetramethyl) glycols and poly(oxytetra-
methyl) diamines include Ubin et al. U. S. Patent No.
3,436,359 patented April 1, 1969 and Leir et al. U. S. Patent
No. 4,833,213, patented May 23, 1989.
Renken et al. U. S. Patent No. 4,618,717, issued Octo-
ber 21, 1986 is directed to a method for reductively aminating
ethylene glycol monoalkyl ethers in order to provide the
corresponding primary amines using a catalyst composed of
about 50 to 90 wt.% of nickel, about 10 to 50 wt.% of copper
and about 0.5 to 5 wt.% of an oxide of chromium, iron,
titanium, thorium, zirconium, manganese, magnesium or zinc.
Larkin et al. U. S. Patent No. 4,766,245, issued August 23,
1988 discloses a method for reductively aminating polyoxy-
alkylene diols and triols in the presence of a Raney nick-
el/aluminum catalyst.
Zimmerman et al. U. S. Patent No. 5,003,107 discloses a
method for the preparation of poly~oxytetramethylene) diamines
by the catalytic reductive amination of a poly(oxytetra-
methylene) glycol feedstock in the presence of hydrogen and
ammonia using a hydrogenation/dehydrogenation catalyst
composed of, on an oxide-free basis, about 70 to 75 wt.% of

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nickel, about 20 to 25 wt.% of copper, about 0.5 to 5 wt.% of
chromium and about 1 to 5 wt.% of molybdenum. The process of
Zimmerman et al. suffers from the disadvantageous need to
convert tetrahydrofuran or an oligomer thereof to a glycol.
SUMMARY OF THE INVENTION
This invention relates to a method for preparing
poly(oxytetramethylene) diamines. Poly(oxytetramethylene)
diamines are useful for the preparation of polyamide and
polyurea elastomers. The poly(oxytetramethylene) diamines are
conveniently prepared from the corresponding poly(oxytetra-
methylene) glycols, commonly referred to as polytetrahydro-
furan glycols. An example is the method of Zimmerman et al.
U. S. Patent Nol 5,003,107, which requires the preparation of
an intermediate glycol derivative of tetrahydrofuran. In
contrast, in accordance with the present invention, poly(oxy-
tetramethylene) diacetate resulting from the polymerization of
'etrahydrofuran is converted to the corresponding poly(oxy-
tetramethylene) diamines by the catalytic reductive amination
in the presence of hydrogen and ammonia using a hydrogenation/
dehydrogenation catalyst composed of, on an oxide-free basis,
about 70 to 75 wt.% of nickel, about 20 to 25 wt.% of copper,
about 0.5 to 5 wt.% of chromium and about 1 to 5 wt.% of
molybdenum.

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DETAILED DESCRIPTION
The starting materials for the present invention are a
nickel, copper, chromia, molybdenum catalyst which may
suitably be a powdered catalyst if the reaction is to be
conducted in an autoclave on a batch basis or a pelleted
catalyst if the reaction is to be conducted on a continuous
basis in a continuous reactor.
The catalyst to be used in conducting the process of the
present invention is suitably a catalyst of the type disclosed
in Moss et al. U. S. Patent No. 3,151,115 wherein reductive
amination catalysts are disclosed containing nickel, cobalt
and copper or mixtures thereof and chromium oxide, molybdenum
oxide, manganese oxide, thorium oxide and mixtures thereof.
Also used as starting materials are ammonia, hydrogen and
poly(oxytetramethylene) diacetates such as a poly(oxytetra-
methylene) diacetate having the following formula:
1l 1l
H3C-C-O-CH2-CH2-CH2-CH2-[-O-CH2-CH2-CH2-CH2-]no CH2 CH2 CH2 CH2 3
(I)
wherein n represents 0 or a positive number having a
value of 1 to about 50.
In accordance with the present invention, a poly~oxy-
tetramethylene) diacetate feedstock is substantially quantita-
tively converted to the corresponding poly(oxytetramethylene)diamine with excellent yields and selectivities when the
reaction is conducted in the presence of a catalyst composed

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of from about 70 to about 75 wt.% of nickel, about 20 to about
25 wt.% of copper, about O.s to about 5 wt.% of chromium and
about 1 to about 5 wt.% of molybdenum.
More particularly, an especially preferred catalyst
composition of the present invention is one containing from
about 70 to about 78 wt.% of nickel, about 20 to about 25 wt.%
of copper, about 0.5 to about 3 wt% of chromium, and about 1
to about 3 wt.% of molybdenum.
The reductive amination reaction of the present invention
is suitably conducted at a temperature within the range of
about 150 to about 220OC. and a pressure of about 100 to
about 10,000 psig., such as a pressure of about 100 to about
3,000 psig.
The reductive amination is conducted in the presence of
ammonia. Suitably, from about 1 to about 300 moles of ammonia
per mole of poly(oxytetramethylene) diacetate are employed,
and more preferably, from about 10 to about 150 moles of
ammonia are employed per mole of poly(oxytetramethylene)
diacetate.
The reaction is also preferably conducted in the presence
of added hydrogen. The amount of added hydrogen used may be
about 0.1 to about 10 mole per mole of poly(oxytetramethylene)
diacetate. Preferably, from about 0.5 to about 80 mole of
hydrogen per mole of poly(oxytetramethylene) diacetate will be
employed.

2~
The process of the present invention may be conducted
batch-wise using an autoclave containing powdered catalyst, in
which case the residence time is suitably from about 0.5 to
about 5 hours.
Mor0 preferably, the reaction is conducted on a continu-
ous basis using a bed of pelleted catalyst through which the
hydrogen, ammonia and poly(oxytetramethylene) diacetate are
passed. When the reaction is conducted on a continuous basis,
the polytoxytetramethylene) diacetate is suitably charged to
the catalyst bed at the rate of about 0.5 grams per hour of
poly~oxytetramethylene) diacetate per cc of catalyst.
The reaction mixture formed as a result of the reductive
amination of the poly(oxytetramethylene) diacetate may be
recovered and fractionated in any suitable manner, such as by
fractional distillation, to obtain unreacted feed components,
by-products and the desired poly(oxytetramethylene) diamine
reaction product. Conversions of 90 wt.% or more and selec-
tivities of 90% or more are obtainable with the process of the
present invention, such that only minor quantities of unre-
acted feedstock and by-products are present in the reaction
mixture.

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EXAMPLES
The present invention will be further illustrated by the
following specific examples which are given by way of illus-
tration and which are not intended as limitations on the scope
of this invention.
The nickel, copper, chromium, molybdenum catalyst used in
conducting the batch and continuous experiments reported in
the examples was a catalyst composed of about 75 wt.% of
nickel, about 21 wt.% of copper, about 2 wt.% of chromium and
about 2 wt.~ of molybdenum.
Preparation of Poly(tetrahydrofuran) Diacetate
Tetrahydrofuran or THF (500 g, 6.9 mol), dried over 4A
molecular sieves, was added to Clay 124 from Englehard (25 g)
followed by distilled acetic anhydride (83 g, 0.81 mol). This
mixture was stirred at 30C for 48 hours. After this reaction
time, the sample was stripped of lights and THF by heating to
75OC under reduced pressure (25 torr). The viscous oil was
placed under minimum vacuum (0.1 torr) and 80C for 1 hour to
give 401 g of product (69% conversion); SAP ~ 3.23 (meq/g),
604 mw by gel permeation chromatography, 6.87 acidity
(mgKOH/g), and 0.03 wt.% water.
Amination of Poly(tetrahydrofuran) Diacetate
A 1-liter autoclave was charged with 100 g of the
diacetate from the above example, 50 g of a Ni-Cu-Co-Mo

X~; o ~1'3?,:~
catalyst, and 150 g of ammonia. The clave was then pressured
to 350 psig. with hydrogen and heated over a 85 minute period
to 220C. It was held at this temperature for 3 hours. The
reaction was then cooled and vented. The catalyst was removed
by filtration and the product was stripped at reduced pres-
sure. It had the following analysis:
Total acet. 0.945 meq/g
Total amine 0.843 meq/g 89% amination
Primary amine 0.642 meq/g 76% o amines
Comparison Example
A 1-liter autoclave was charged with 299 g of a 2000
molecular weight polytetrahydrofuran polyol, 48 g, of a Ni-Cu-
Co-Mo catalyst, and 90 g of ammonia. The clave was then
pressured to 350 psig. with hydrogen and heated over a 46-
minute period to 220C. It was held at that temperature for
3 hours. The reaction was then cooled and vented. The
catalyst was removed by filtration and the product stripped at
reduced pressure. The product had the following analysis:
Total acet. 0-.847 meq/g
Total amine 0.688 meq/g 81% amination
Primary amine 0.556 meq/g 81% of amines
What is claimed is: